Rubric Lakes Or Field's Lakes Are Derived From The Root Of Rubia





tinctorum," a plant largely grown in France and Holland, whence the bulk

of that used in England is obtained. The French madders are in a state

of very fine powder, containing one half their weight of gum, sugar,

salts, and other soluble substances, which water speedily dissolves.

Madder roots in the unground state are imported from the Levant, and

called Turkey roots. Good qualities of Turkey madder yield near sixty

per cent of extractive matters, a term that includes everything

removable by water and dilute alkalis: the woody fibre is therefore

about forty per cent. This is presuming the root to be genuine, for

madder is often adulterated with brickdust, red ochre, red sand, clay,

mahogany sawdust, logwood, sandal and japan-wood, and bran.



Unlike cochineal, madder possesses several colouring matters; the

question of which, despite the learned researches of Dr. Schunck and

others, is far from settled yet. The following remarks embody our own

experience of the root, simply as a pigment-producing product:--



Madder contains five colouring matters--yellow, red, orange, purple, and

brown. Of these, the first colour is soluble in cold water. By washing

the powdered root quickly with it by decantation, the yellow and brown

are extracted in the form of an opaque liquid. If this be decanted and

allowed to stand, the brown deposits, leaving a clear buffish-yellow

supernatant liquor. In the root from which the extract was poured, the

remaining three colours are left. On adding a strong boiling solution of

alum, these are dissolved, yielding a fine red liquid. From this there

can be thrown down, by the agency of different chemicals, a red, an

orange, or a purple precipitate. Or, supposing the whole of the

colouring matter to be deposited as a red lake, it is possible to

convert this--also by the agency of different chemicals--either into

orange or purple. Hence, for all practical purposes, madder contains but

three colouring matters: a yellow, soluble in cold water; a brown, not

soluble in, but capable of being extracted by cold water; and a red,

soluble in boiling alum, and furnishing at will a purple or an orange.



As was observed in the previous chapter, no good pigment is obtained

from the yellow, of which the less there is present the better; but the

brown affords a valued product, which will be duly noticed. It is

essential to the purity of the reds, that the madder should be freed

from both these colours; and it was probably due to insufficient aqueous

washing of the root, that the old lakes were dull and muddy, mere

brick-reds of ochrous hues. For many years, however, lakes have been

prepared perfectly transparent, and literally as beautiful and pure in

colour as the rose; qualities in which they are unrivalled by the lakes

and carmine of cochineal. They have justly been considered as supplying

a desideratum, and as among the most valuable acquisitions of the

palette in modern times, since permanent transparent red and rose

pigments were previously unknown. The red varieties range from rich





Rubiate Or Liquid Madder Lake Russet Hues Of Autumn Foliage Where Purple And Orange Have Broken Or facebooktwittergoogle_plusredditpinterestlinkedinmail

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